Turbocharged and supercharged internal combustion engines may be configured to compress ambient air in order to increase power. Compressing the ambient air may cause an increase in air temperature, causing a decrease in engine power due to the intake of high-temperature air. To decrease the ambient air temperature an intercooler (or charge air cooler, CAC) may be placed in between the compressor and intake manifold. By reducing the temperature of the ambient air, its density increases thereby allowing the engine to produce more power. However, as the hot air passes through the intercooler and cools off below the water dew point, condensate (in the form of liquid water mixed with other particulates or fluids) may form and collect inside the intercooler and its passages. Condensation levels may also increase due to increased humidity or rainy weather conditions, where the ambient air is holding an increased amount of water. When engine torque is increased during acceleration or other similar conditions, the resulting increased mass airflow may draw the condensate from the intercooler into the engine, thus increasing the chance of engine misfire and combustion instability.
One method to address the issue of condensate formation in the intercooler involves draining condensate from the intercooler via a removal valve. Many types of valves and valve systems exist for purging the intercooler of condensate. However, one major problem that arises from using removal valves is that during valve opening events a direct fluidic connection between the interior of the intercooler and an outside forms, thereby allowing both condensate and compressed air to escape. The loss of compressed air may decrease boost pressure to the engine and cause miscalculations in the amount of intake air, thereby reducing engine performance.
In one approach to avoid direct connection between the boosted air and the outside environment, shown by Appleton in U.S. Pat. No. 7,251,937, two valves and a water reservoir are used to drain condensate from the CAC. A check valve leads from the CAC to a water reservoir and a pilot operated valve leads from the water reservoir to the environment. Depending on the pressure within the CAC the two valves open and close, utilizing springs and a pilot line to ensure that the valves are neither both opened or closed at the same time so the CAC is always isolated from the environment. The condensate draining system operates in a number of states depending on the CAC pressure, wherein condensate drains from the CAC to the reservoir via the check valve and from the reservoir to the environment via the pilot operated valve. Additionally, during periods of constant pressure in the CAC, the number of states may not cycle resulting in the check valve remaining closed and condensate accumulating in the CAC.
However, the inventors herein have identified potential issues with the approach of U.S. Pat. No. 7,251,937. If the valve springs were to malfunction or the opening and closing states were mistimed a direct fluidic connection between the CAC and environment would form, leading to the aforementioned results. Furthermore, the use of multiple valves unnecessarily increases the complexity of the draining system.
Thus in one example, the above issues may be addressed by a method for condensate removal comprising: collecting condensate from an intercooler into a collection region; moving the condensate through an orifice into a cavity of a hollow valve in a first position; and shuttling the valve to a second position to release the condensate to an exterior side of the intercooler. In this way, boosted air from the intercooler cannot continuously escape to the exterior atmosphere while still being able to effectively drain condensate from the intercooler.
For example, the valve assembly used to move the condensate from the interior to exterior of the intercooler may include a condensate collection region (e.g. container) and a hollow valve. The collection region allows condensate to flow into the hollow valve via an orifice, with the hollow valve in a first or closed position. Upon a boosted air pressure within the intercooler the valve may move to the exterior of the intercooler in a second or open position such that the condensate can drain to the exterior environment via the same orifice. The hollow valve may then move back to the closed position. As the hollow valve moves back and forth in a shuttling manner, condensate is continuously removed from the intercooler without forming a direct connection between the compressed air and atmospheric air. The shuttling motion of the valve depends on the pressure fluctuations within the intercooler.
For times when there is no substantial air pressure change within the intercooler, an electric actuator may be attached to the valve such that it operates when the mechanical pressure activation of the valve temporarily stops. A control scheme may be implemented such that a timer measures the duration of a constant pressure event and if a pre-determined time elapses such that the pressure does not substantially change, then a controller signals the actuator to shuttle the valve for a period of time or number of cycles.
In addition to the electronic actuator, the valve assembly may be equipped with a heating element that is utilized during cold weather situations. The heater may be located on a surface of the valve assembly such that it is near the liquid condensate in the collection container and hollow valve. During cold weather the heater would keep the condensate above freezing temperatures allowing for the continuous removal of condensate from the intercooler.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.